Method of making nails



March 5, 1935. R. .1; FARRELL METHOfi OF MAKING NAILS Patented Mar. 5, 1935 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to wire nails and more particularly to a method of manufacturing wire nails having a cupped end and mechanically roughened surface.

Generally wire nails are now made with a pointed end square in section, such nails being known in the art as diamond-point nails. To increase theholding qualities of such a nail, it is common practice to apply, as a separate and distinct step, a coating, such as cement, to the shank of the nail or to roughen the surface of the shank. The most common methods for roughening the surface now in use are etching, sand-blasting and barbing.

In the etching process the rough surface is secured by corroding the body of the nail in an acid bath, and after a sufficient amount of corrosion has taken place, the nail is neutralized by immersion in an alkaline solution and then dried. This method of roughening the surface of a nail has proven to be so expensive that there is a grave question as to its practicability, because it is necessary to handle the nails frequently during the process of manufacture.

The sand-blasting method of roughening the surface has also proven more or less unsatisfactory in commercial use. In that method the nails are sanded while they are being conveyed on an endless vibrating belt and due to the dust and grit occasioned by the sanding, this process must be carried on at a place some distance from the nail machine to prevent this dust and grit from working into the bearings of the machinery. Thus the nails, after being made must be handled and conveyed to the sanding apparatus.

Further, it is practically impossible to secure a uniformly roughened surface by the sand-blasting process, since the turning of the nails into the path of travel of the particles of sand depends entirely upon the vibration of the belt. As a result the nails are frequently pitted on one side only thereby destroying the purpose for which the pitting was intended. This criticism also applies to a great extent to the etching operation.

The most common method of rougheningthe surface of nails is by the formation of barbs along the length of the shank. These barbs are usually formed by hitting the shank of the nail with dies which in effect scoop out or groove the surface and distort the shape of the nail. Roughening the surface by this method not only weakens the nail but the scooped out metal projects beyond the body which, when the nail is driven, tears a ragged hole and thus destroys the wood fibers immediately adjacent the body of the nail, and therefore decreases, rather than increases the holding power of the nail.

- In all of the processes known to me and now in'use for roughening the surface of the nail, the

surface is roughened as a separate step either before the nail is formed, as in barbing, or after the nail has been completely manufactured, as in etching and sand-blasting, thus materially increasing the manufacturing costs of the nail.

It is an object of the present invention to roughen the surfaceof a nail while some other step in the operation of forming the'nail is being performed, and in this way to, in effect, reduce the number of operations to which the nail is subjected during manufacture. 7

Another object is to provide a method of mechanically working the shank of a nail to secure a uniformly roughened surface whereby the frictional tendencies of the surface will be greatly increased. 7

Another and more specific object is to produce' a nail which will not split the wood into which it is driven and which has greatly increased holding power. k

A further object is to cheaply and effectively produce a roughened surface on the body of the nail which is such that the holding or gripping power of the wood fibers adjacent the body of the nail will not be destroyed or weakened during the operation of driving the nail.

A still further object is to provide a method of uniformly roughening the surface of a nail which will be inexpensive, does not increase the cost of manufacture, and which may be performed simultaneously with the formation of the point on'the nail.

These and other objects which will be hereinafter made apparent to those skilled in this particular art are accomplished by means of this invention, one embodiment of which is described in the following specification in conjunction with the drawing, illustrating apparatus for carrying out such embodiment, and wherein:

' Figure 1 is a sectional view of an apparatus for shaping the point and roughening the surface of a nail blank; I

Fig. 2 is a partial front viewof the b'ack'pointing and knurling dies;

Fig. Bis a diagrammatical view illustrating th steps performed in roughening the surface and. pointing the end of a nail blank; 1

Fig. 4 is a top plan of the apparatus illustrated in Fig. 3; and

Fig. 5 is a plan view of the pointing dies. In general, my invention consists in subjecting a nail blank (preferably after it has been cut to length and headed) to a rotative force and simultaneously distorting the surface of thebody thereof to produce pits or depressions therein which are more or less uniformly distributed around the body portion and throughout at least the major portion of the length thereof. The

rotativelfo'rce may be applied by means of the I instrumentalities which accomplish the pitting or roughening operation, and where the nail forming operation is such that the nail is subjected to a pointing operation while being rotated then the knurling or pitting operation may be performed simultaneously with the pointing operation. In any event, the knurling or pitting operation is preferably accomplished simultaneously with some other operation employed during the manufacture of the nail, whether that operation accomplishes a change in the form of the blank or merely a change in the position of the blank with relation to the instrumentalities acting on the blank. As an example thereof, I contemplate either performing the knurling or roughening operation during the operation of pointing the endof the blank, or I employ the instrumentalities which accomplish the roughening operation as a transfer mechanism for moving the blank from one set of instrumentalities to another.

In carrying out my invention the wire from which the nails are to be made is fed from a coil into a commercial nail machine which heads the end of the wire and cuts it to length, the cutbeing in a plane transverse to the longitudinal axis thereof. After the blank has been formed it isfed into a suitable magazine such as that disclosed in my copending application, Serial No. 568,662, filed October 14, 1931, and commonly employed in nail driving machines which feed the blanks 9 one at a time into tubes 10, the end of one of which is shown.

As the blank drops through the tube 10 it passes through a slotted plate 11 into a spring clip 12 secured to the end of the tube 10 which positions the cut end ofthe blank between dies 13 and 14, the opposed faces of which are inclined one to the other. The die 13, hereinafter called the front die, is slidably mounted in a frame 15 secured to a frame 16 and when the machine is in operation is continually reciprocated by suitable mechanism (none shown). The die 13 carries a die or race 17 having a knurled face 18. The knurling die 1'7 is mounted in members 19 bolted to the top of the die 13.

In order to adjust theposition of the knurling face 18 the heads of the bolts securing the members 19 to the die 13 are mounted in recesses 19a, formed in the die 13. The die 14 or back die, is mounted in a frame 20 which has a groove and slot connection with supports 21 carried on the frame 16. This die, which is movable into and out of operative engagement with the die 13 by a cam 22 mounted on a shaft 22a continuously driven in any suitable manner, carries a die 23 having a knurled face 24. The knurling die 23 is adjustably mounted in members 25 secured to the top of the die 14 the lower ends of which are received in slots 26 formed in the die 23, and terminate in upstanding lugs 27 projecting into cavities 28 opening into the slots 26. The upper end of the die 23 is provided with a flange 29 which normally bears against lugs 30 depending from the frames 25. The die 23 is held in its forward position by'means of springs 31 and it is therefore self-adjusting with relation to the cooperating die 17.

These spring members 31 yieldably hold the knurled surface 24 of the die 23 against the body of the blank 9 and therefore the relative positions of the dies 1'7 and 23 are automatically adjusted to take care of small variations in blank gauge or diameter. The upper ends of the frames 25 are mounted in an inverted channel shaped that the cycle of operation is such that the dies 1 14 and 23 first move toward their respective cooperating dies 13 and 17, and then the dies 13 and 17 move longitudinally. At the termination of this longitudinal motion the dies 14 and 23 move outwardly or away from the dies 13 and 17 and the cycle is then repeated. The time relation is such that as a blank 9 moves into position between the dies 131'7 and 1423, the dies 1317 start their longitudinal movement, and then the dies 14-23 move toward them or into blank engaging position. The blank is rotating as it is engaged by the dies 1423, or the initial engagement of the dies 14-23 with the blank occasions rotation of the blank, so that there is no possibility for the opposed dies to flatten the surface of the blank. This rotation of the blank causes it to move transversely of its longitudinal axis or along the face of the die 17, with the relongitudinal axis between said faces causes the metal adjacent the end of the blank to be extruded beyond the central core of the blank and tapered to conical form, thereby forming a closed annular cutting edge and a concave surface on the end of the nail which is slightly smaller in diameter than the body of the nail.

At the same time that the point is being cupped and tapered, the surface of the nail is distorted by the knurled surfaces 18 and 24 and depressions are formed therein. The continued rolling of the blank about its longitudinal axis rolls down any projections which might be formed on the body of the nail by theknurling dies and as a result, all of the parts of the surface are within the true diameter of the shank. Thus, when the nail is driven the area of wood displaced is only that of the area of the true circle of the body of fill the nail and there are no projections on the body to tear a ragged hole in the wood.

,In Figs. 2 to 5, inclusive, I have shown another apparatus for carrying out my invention. In this apparatus the blank after it has been cut by the shaft 45 has a bevel gear 46 on one end thereof which meshes with a bevel gear 47 on a shaft 48 continuously driven from a suitable source.

As soon as the blank comes in contact with the knurled surface 43 of the endless member 42 it is caused to travel along the side of an oppositely disposed die member 49 which is yieldably pressed toward the endless member by springs 49a. Thedie 49 has a knurled surface 50 and the continued movement of the endless die member 42 carries the blank along the guides 40 and rolls it about its longitudinal axis between the knurled surfaces 43 and 50 whereby a roughened surface is formed thereon all particles of which are within the original diameter of the blank.

When the nail has travelled the full length of the die members 42 and 49, it slides on an inclined portion of the guides and 41 and the end thereof is positioned adjacent to the side of a circular die member 51 having its upper edge inclined as at 52. When the blank is in this position it is engaged by a constantly rotated cam 53 having a face 54 inclined oppositely to the face of the die member 51. The rotation of the cam 53 relative to the die 51 rotates the blankabout its longitudinal axis, and pulls it from the guides 40 and 41. The faces 52 and 54 of the die and cam are so inclined that a flow of metal is occasioned between the outer surface adjacent the end of the blank and the central core thereof whereby the surface metal is extruded beyond the end of the blank forming a concave surface thereon and tapered to conical form thereby forming a closed annular cutting edge of slightly smaller diameter than the diameter of the nail. The cam 53 is mounted on a shaft 55 which is constantly driven from a suitable source.

To insure the entrance of the end of the blank between the inclined surfaces 52 and 54, the cam 51 may be eccentrically mounted whereby a continually increasing angularly directed pressure is applied to the end of the nail blank. To prevent the blank frcm moving upwardly when engaged by the rotating cam 51, a plate member 56 is placed over the top of the guide members 40 and 41. When the cam 51 has moved past the end of the nail blank, the completed nail falls through the die 51 into a keg or other receptacle.

As shown, the cam 53 is concentric with the operating face 52 of the die 51, but the operating face 54 thereof is eccentric to the face 52, consequently the two opposed dies engage the point of the blank 9 with a progressively increasing pressure but the initial engagement is such as to merely ensure rotation of the blank.

From the foregoing it is apparent that the operations performed on the blank, produce a nail having a cupped, tapered end and a roughened or knurled body portion. The cupped end provides a cutting edge at the entering end of the nail of slightly smaller diameter than the body of the nail, and which acts, on driving the nail, to cut a smooth bore of slightly smaller diameter than the body of the nail, and the taper on the entering end of the nail is such that the cut wood fibers are distorted or compressed so as to permit the body of the nail to enter the bore so cut. The knurling of the surface of the nail body is such that these out wood fibers will not be torn or unduly displaced by the nail driving operation, with the result that the inherent resiliency of the wood will force the cut fibers into the pits or knurls, and thus increase the holding qualities of the nail over smooth or knurled nails, when the knurling is such as to tear the wood fibers.

The roughening operation is so performed that the blank is rotated between the knurling surfaces, even after the knurling is accomplished, with the result that any ragged or projecting points which may have been formed thereon are ironed down and the knurled surface is all of substantially the same diameter as the body of the nail.

While in the disclosure only one of the dies,

which imparts the rotative force to the nail blank, is reciprocated or rotated, it is understood that both dies may be reciprocating or rotating in opposite directions without departing from my invention, the cupping and roughening being accomplished by the frictional contact of the dies with the nail blank.

It is further apparent that in my process of manufacturing wire nails, the surface may be roughened at the same time that the point is formed or it may be roughened while the nail blank is being conveyed from the heading and cutting machine to the pointing dies. In either event, no extra handling of the nail blank is necessary and as a result, the nail can be manufactured at a very low cost.

What I claim as new and desire to secure by Letters Patent is:

1. The method of cupping the end and roughening the surface of a nail blank, which consists in applying an angularly directed extruding and rotative force to the end of the blank while the shank is held against a knurled surface and in continuing the application of such force to draw the surface metal adjacent the end of the blank beyond the central core thereof to cup and taper the end of the blank and to roughen the surface thereof.

2. The method of cupping the end and roughening the surface of a nail blank which consists in rotating the blank about its longitudinal axis, applying a distorting pressure to the shank of said blank while it is being rotated and then applying an angularly directed force to the end of said blank while continuing the rotation thereof to taper the end and cause the surface metal adjacent the end of the blank to flow beyond the central core thereof.

3. The method of manufacturing nails which consists in applying a rotative force to a nail blank while the shank is in contact with a knurled surface, and continuing the application of said rotative force while an extruding and tapering force is applied to the end of the blankto occasion the surface metal adjacent the end of the blank to flow beyond the central core thereof and form a tapered cup-shaped entering end on said nail.

4. The method of manufacturing nails which consists in applying a rotative force to a nail blank, roughening the surface of the shank'while the blank is rotating, and then in occasioning a relative flow between the surface metal and the central core of the blank at the end thereof by the application of an angularly directed force thereto while continuing the rotation of the blank to taper and cup the end of said blank.

5. The method of manufacturing wire nails which consists in drawing the surface metal adjacent the end of a nail blank beyond the central core thereof to cup and taper the end of the blank and applying a roughening force to the surface of said blank while rotating the blank about its longitudinal axis.

6. The method of manufacturing nails which consists in cupping the end of a nail blank by extruding and tapering the surface metal thereof while said blank is being rotated about its longitudinal axis, and in continuing the rotation of said blank while the shank thereof is held a ainst a knurled surface.

ROBERT J. FARRELL. 

